It’s December 1942, and New York’s little-radio-station-that-could, WOV, is about to air its final broadcast of the holiday-themed Mutual Manhattan Variety Cavalcade. That’s the setting for The 1940’s Radio Hour, a timeless play full of classic tunes sung in four- and five-part harmony. With its dance routines, swinging music — including “Ain’t She Sweet,” “Blue Moon,” “You Go to My Head” and “Have Yourself a Merry Little Christmas” — and beloved cast of characters, Radio Hour is a perfect holiday treat.